Rosemary (Rosmarinus officialis) is a woody perennial herb with fragrant evergreen needle-like leaves native to the Mediterranean region. It is known as an herb commonly used in Mediterranean cuisine. Its dried form is high in iron, calcium and Vitamin B6. It also contains a carnosol, a polyphenol, which is an antioxidant and has recently been described as an anti-carcinogen (Lo et al 2002 Carcinogenesis 23(6):983-991), working by suppressing the NF-κB pathway.
Lipophilic rosemary or sage extracts contain approximately 10-30% carnosic acid.
A process for synthesizing carnosol from carnosic acid was published by Marrero et al 2002 J. Natural Products 65:986-989. A “quantitative conversion” to carnosol is described whereby carnosic acid is dissolved in acetone and molecular oxygen was bubbled through the solution. However, despite numerous repetitions of this scheme, it was not repeatable, and virtually no carnosol was formed.
It would be desirable to have an easy, efficient process for transforming the carnosic acid into the biologically active form carnosol, especially if the extraction and transformation were essentially the same step.